Process of refining glyceride oil in a liquid paraffinic solvent with a concentrated alcoholic alkali metal hydroxide solution



Oct. 14, 1952 AYERS 2,614,111

PROCESS OF REFINING GLYCERIDE OIL IN A LIQUID PARAFFINIC SOLVENT WITH A CONCENTRATED ALCOHOLIC ALKALI METAL HYDROXIDE SOLUTION Filed Jan. 4, 1949 HOIDVHLXB NOLLV'HLLSIG HSV'IJ INVENTOR.

A.L. AYERS M5 v. {E N R O T T A Y Patented Oct. 14, 1952 PROCESS OF'REFINING GLYCERIDE OIL IN A LIQUID 'PARAFFINIC SOLVENT WITH A CONCENTRATED ALCOHOLIC ALKALI METAL HYDROXIDE SOLUTION Arnold L. Ayers, Bartlesville, 0kla., assignor t0 Phillips Petroleum Company, a corporation of Delaware Application January 4, 1949, Serial No. 69,104

14 Claims. 1

This invention relates to a method of treating glyceride oils. Ina .more specific aspect, it relates to a method of treating glyceride oils to remove undesirable constituents. In another specific aspect, it relates to a method for removing free fatty acids, color bodies, non-drying constituents, and break formers from a glyceri'de oil. .In still another specific aspect, it relates to a single-treatment methodof refining glyceride oils. More specifically, it relates to a method of refining soy bean oil. c

The glyceride oils with which this invention is concerned, are animal and vegetable oils, the latter of which are obtained from seeds, usually by pressing or by extraction with a suitable solvent. Some of the commonly used glyceride oils are linseed oil, tung oil, soy bean oil, cotton seed oil, corn oil, and peanut oil. While these oils have wide use in the preparation of foods, my invention is likewise concerned with the preparation of these oils as film-forming constituents, such as in paints, varnishes, enamels, synthetic resins, soap, plastics, drug products, and the like.

Ordinarily, glyceride oils, both those obtained by pressing and by extraction with solvents contain about 0.5 to 1 per cent of phosphatides and 1 to 2 per cent of free fatty acids. In addition, there is a certain content of color bodies, nondrying constituents, and materials which cause break or sludge formation upon heating. In preparing oils for such industrial uses,it isinecessary'that these undesirable constituents be removed.

Conventional methods of refining vegetable oils involve the use of large volumes of concentrated.

reagents such as sulfuric acid or sodium hydroxide, which often tend to char or coagulatethe by-products :of the oil. In addition, these reagents have a harmful effect .on .the. drying or film-forming characteristics of the oil. In my copending application, Serial No. 17,105, filed March25, 1948, for A Process for Refining Soy 'Be'an'Oil, I have disclosed a method of refining soy bean oil comprising the steps of extracting the oil with an alcohol-water solution followed by treatment with a dilute caustic solution.

I have now discovered a method of refining vegetable oils which involves a single treatment with an alcoholic solution of an alkali metal hydroxide.

It is therefore an object of my invention to provide a method .for refining glycerid'e oils wherein a minimum amount of equipment is required.

It is another object of my invention to provide a 2 a method for removing :undesirable constituents from a glyceride oil.

It is still another .object of .my invention to provide .a single-treatment method for refining glyceride oils.

It is another object of my invention to'provide a method for refining soy bean oil with aminimum loss of oil.

Other objects and advantages of my'invention will be apparent'to those skilled in the art upon reading the following drawing, disclosure and claims.

The single drawing is a flow sheet showing the steps involved in a continuous process for the refining of glyceride oils according to my invention.

In the drawing, raw oil feedline 2 .and hydrocarbon solvent feed line 3 lead to mixer 4, from which outlet line 6 leads to extractor"! 'for transferring the solvent-oil niiscella' from said mixer to said extractor. Entering the top of extractor l is a feed line 8 for introducing alcoholic caustic solution and leaving the bottom of said extractor is an outlet line 9 for removing the spent caustic. Leaving the top of said extractor is an outlet line 10 for transferring the miscella to a separator l l for complete removal of the spent caustic through line l2. From said separator, a miscella outlet line [3 leads to flash distillation chamber M from which the vaporized hydrocarbon leaves an upper portion through line 16 and the refined oil leaves at the bottom through line H. Hydrocarbon vapor line l6 enters condenser 18 "from which the condensed hydrocarbon is removed through line 19 into hydrocarbon feed line -3.

Operation I have found that glyceride oils can be refined by a single treatment with an alcoholic solution of an alkali metal hydroxide. To my knowledge, it has never been tried or even realized that'the extraction and neutralization steps could be combined into a single treatment, but I have found thatglyceride oils can be efiiciently refined by such asingle treatment.

In carrying out my invention, I prefer to form a solvent-oil miscella by dissolving one part of alcohol, ethyl or isopropyl alcohol may be used instead. It is not necessary that absolute alcohol be used but the alcoholic content should be between 75 and 100 per cent, the higher water contents being desirable when operating at higher temperatures, as hereafter disclosed. I may use from 0.02 to 5 grams of alkali metal hydroxide per 100 grams of oil treated, the exact amount extraction, I prefer that the contact time be between 5 and minutes and that the temperature be between 0 and 30 0., although tempera' tures between 20 to 130" C. may be employed. K

The pressure is adjusted to maintain the reactants in the liquid phase.

lThevolume ratio of alcohol to glyceride oil should be from 0.2 1 to :1, the preferred range beingfrom 2:1 to 20:1. I

,After contact between the miscella and alcoholic caustic has been maintained for a sufficiently long time, the mixture is allowed to settle and the oily miscella is separated from the spent caustic solution. The oil and spent caustic solutions can be separated by gravity when operating under preferred conditions of high solvent to oil ratio because the miscella will be of suificiently low density, to allow the spent caustic to settle. However, when the specific gravity of the miscella and the caustic solution are more nearly equal, the separation may be made by means of a centrifuge or its equivalent.

. The paraffinic solvent added to the oil in forming the. original miscella is removed by distillation, preferably, at atmospheric pressure, the temperature vto which it must be heated, of course, being dependent on the boiling point of the solvent used. It is not desirable to heat the oil to a much higher temperature than is necessary to distill the solvent.

After such a treatment as I have just described. the refined oil will be of good color and will ordinarily contain less than 0.1 per cent of free fatty acid. The content of the break or sludge formers will be correspondingly lowered. 1

My invention may be'carried out as a batch process or the process may be continuous, as shown in the drawing. The drawing represents the apparatus adapted to carrying out a process wherein the density of miscella is suificiently below that of the caustic solution to permit countercurrent flow of liquids through the extractor. The separator, which maybe a centrifuge or any equivalent, permits more complete separation of miscella and spent caustic.

By carrying out the neutralization and alcohol extraction in a single step, the process is considerably simplified. The amount of equipment is reduced because one extractor and separator are used to carry out a treatment formerly requiringtwo reactors and two separators. This means ashorter treating cycle for refining the oil than is required in the two-stage process. Reducing theamount of equipment also reduces thecapital investment, which means an increased amount of material may be processed per unit cost. Another advantage of reduced amount of equipment is areduced amount of oil lost during processing because of leaks in equip- Sodium,

ment and oil dissolved in treating liquids. Eliminating one step of the process reduces the operating and maintenance costs.

In my process the concentration of caustic in the alcohol-caustic treating fluid is. lower than the concentration normally employed in the neutralizing fluid of a two-step process. This means less corrosion of equipment and less hydrolysis of the oil during treatment. Numerous other advantages will be apparent to those skilled in the art.

The use of mixtures of the suitable solvents and/or mixtures of the caustic materials is fully within the intended scope of my invention. My invention may be employed in the refining of innumerable oils which can be refined by caustic treatment and alcohol extraction.

The advantages of my invention will be more clearly'understood from the following examples Example I A miscella of 25.6 grams of soybean oil in grams of neohexane was treated with 100 grams of 99% methyl alcohol containing 0.04 gram of sodium hydroxide. The mixture was shaken well and allowed to separate. The two phases were separated by decanting. The oil was recovered from the hydrocarbon phase by vaporizing off the hydrocarbon at atmospheric pressure and a temperature of 60 C. A total of 25.4 grams of refined oil containing only 0.085% free fatty acid was obtained.

Example 11 A miscella containing 26.3 grams of oil in 106 grams of neohexane was heated and mixed with 100 grams of 99% methyl alcohol containing 10 ml. of a 0.1052 N-potassium hydroxide solution. The mixture was allowed to settle and the hydrocarbon phase was separated by decanting. The hydrocarbon was removed from the oil by distillation at atmospheric pressure and a temperature of 60 C. Twenty-six and four-tenths grams of refined oil was recovered. This oil was light colored and contained only 0.058% free fatty acid. (The slight excess yield of refined oil isprobably due to incomplete removal of solvent.)

The specific examples are presented to illustrate and explain the advantages of my process and are not to be considered as limiting my invention, the scope of which is defined by the following claims.

Iclaim:

1. The process of refining a glycerlde oil which comprises intimately contacting a solventoil miscella comprising a solution of said oil in from 1 to 6 volumes of a liquid hydrocarbon for a period of time from 5 to 30 minutes at a temperature of from 20 to C. with an alcoholic alkali metal hydroxide solution consisting essentially of from '75 to 100 per cent alcohol, 0.02 to 5 grams of alkali metal hydroxide per 100 grams of oil and water whenever the concentration of the alcohol employed is less than 100 per cent the ratio of alcohol to oil being from .2 to 50 volumes of said alcohol per volume of oil, separating the miscella from the caustic solution and separating the resulting miscella into the solvent and oil fractions.

2. The process for refining a glyceride oil which comprises intimately contacting a solventoil miscella comprising a solution of said oil in from 1 to 6 volumes of a liquid parailinic hydrocarbon for from 5 to 10 minutes at a temperature from 0 to 30 C. with an alcoholic alkali metal hydroxide solution consisting essentially of 75 to 100 per cent alcohol, 0.02 to 5 grams of alkali metal hydroxide per 100 grams of oil, and water whenever the concentration of the alcohol employed is less than 100 per cent, the ratio of alcohol to oil being from .2 to 50 volumes of alcohol per volume of oil, separating the miscella from the caustic solution and separating the resulting miscella into the solvent and oil fractions.

3. The process for refining a glyceride oil which comprises intimately contacting a solventoil miscella comprising a solution of said oil in from 1 to 6 volumes of a liquid parafi'inic hydrocarbon for from 5 to 10 minutes at a temperature from 0 to 30 C. with an alcoholic caustic solution containing essentially from 75 to 100 per cent alcohol, 0.02 to 5 grams of alkali metal hydroxide per 100 grams of oil, the ratio of alcohol to oil and water whenever the concentration of the alcohol employed is less than 100 per cent, being from 2 to volumes of alcohol per volume of oil, separating the miscella from the caustic solution and separating the resulting miscella into the solvent and oil fractions.

4. The process for refining a glyceride oil which comprises intimately contacting a solventoil miscella comprising a solution of said oil in from 1 to 6 volumes of a liquid paraffinic hydrocarbon for from 5 to 10 minutes at a tempera ture from 0 to C. with an alcoholic caustic solution containing essentially from 75 to 100 per cent methyl alcohol, from 0.02 to 5 grams of alkali metal hydroxide per 100 grams of oil and water whenever the concentration of the alcohol employed is less than 100 per cent, the ratio of alcohol to oil being from 2 to 20 volumes of said alcohol per volume of oil, separating the miscella from the caustic solution and separating the resulting miscella into the solvent and oil fractions.

5. The process of refining a glyceride oil which comprises intimately contacting a miscella of said oil in a liquid parafiinic solvent with a, concentrated alcoholic alkali metal hydroxide solution consisting essentially of 75-100 percent alcohol, alkali metal hydroxide, and water whenever the concentration of the alcohol employed is less than 100 percent, for a period of time sufiicient to neutralize the free fatty acids and to extract the alcohol-soluble bodies, separating the spent alcoholic caustic solution from the miscella and separating the paramnic solvent from the refined oil.

6. The process of claim 5 wherein the alcohol is methyl alcohol.

7. The process of claim 5 wherein the alcohol is ethyl alcohol.

8. The process of claim 5 wherein :the alcohol is isopropyl alcohol.

9. The process of claim 5 wherein the paramnic solvent is neohexane.

10. The process of claim 5 wherein the paraffinic solvent is n-hexane.

11. The process of claim 5 wherein the paraffinic solvent is n-pentane.

12. The process of claim 5 wherein thealkali metal hydroxide is sodium hydroxide.

13. The process of claim 5 wherein the alkali metal hydroxide is potassium hydroxide.

14. The process of refining a crude soy bean oil which comprises intimately contacting a miscella of one volume of said oil in from 4 to 6 volumes of neohexane at a temperature between 0 and 30 C. for a period of time from 5 to 10 minutes with a. to per cent methyl alcohol solution containing from 0.02 to 5 grams of alkali metal hydroxide per 100 grams of oil, separating said miscella from the spent alcoholic caustic solution and heating the separated miscella to distill the parafiinic solvent.

ARNOLD L. AYERS.

REFERENCES CITED The following references are of record in' 'the file of this patent:

UNITED STATES PATENTS Number Name Date 1,194,013 Handy et al Aug. 8, 1916 1,729,809 Wilhelm Oct. 1, 1929 2,113,942 Jones Apr. 12, 1938 2,190,590 Clayton Feb. 13, 1940 2,268,786 Dijck Jan. 6, 1942 FOREIGN PATENTS Number Country Date 252,370 Great Britain 1927 5 Great r tain Rename-a... 9 7 

5. THE PROCESS OF REFINING A GLYCERIDE OIL WHICH COMPRISES INTIMATELY CONTACTING A MISCELLA OF SAID OIL IN A LIQUID PARAFFINIC SOLVENT WITH A CONCENTRATED ALCOHOLIC ALKALI METAL HYDROXIDE SOLUTION CONSISTING ESSENTIALLY OF 75-100 PERCENT ALCOHOL, ALKALI METAL HYDROXIDE, AND WATER WHENEVER THE CONCENTRATION OF THE ALCOHOL EMPLOYED IN LESS THAN 100 PERCENT, FOR A PERIOD OF TIME SUFFICIENT TO NEUTRALIZE THE FREE FATTY ACIDS AND TO EXTRACT THE ALCOHOL-SOLUBLE BODIES, SEPARATING THE SPENT ALCOHOLIC CAUSTIC SOLUTION FROM THE MISCELLA AND SEPARATING THE PARAFFINIC SOLVENT FROM THE REFINED OIL 